Assuming of course, you already have a MAFS for 24lbs.
The only PCM that already took into account 24lb injectors for a Mustang would be the 93 Cobra...good luck finding one. You should try eBay.
Technically speaking, having a 24lb MAFS helps the PCM understand your injector size, but a turner such as the Tweecer would allow you to control that in the PCM.